Stereoscopic applications require calibration of the intrinsic and extrinsic camera parameters. Intrinsic camera parameters, such as focal length and principal point offset, may be determined using a traditional camera calibration approach such as using a checkerboard of known dimensions. Extrinsic camera parameters, such as the rigid body motions between the camera coordinate systems or between a camera and the laser (or world) coordinate systems, may in some cases also be determined using the checkerboard approach. However, accurate extrinsic camera calibration requires a calibration scene similar in dimension (width and depth) to that of the intended application. The determination of extrinsic parameters in certain applications, such as long-range applications, would require an impractically large checkerboard.
Thus, extrinsic calibration methods for long-range applications generally use an array of 3D control points with accurately known positions in the world coordinate system. Construction of the 3D control points is time consuming, expensive and must be specifically constructed for each test site and stereoscopic application. Accordingly, an extrinsic camera calibration method is needed that does not require an accurate array of 3D control points, that requires minimal setup time, and that naturally expands to the required scene dimensions.